Modeling Matter

Modeling Matter

Students will explore the idea that matter is made of particles and learn about technologies that provide evidence for the particle theory of matter.

Can you tear paper in half forever?

Consider a thought experiment in which you tear a piece of paper in half. Then tear it in half again and then again. How many times could you continue this? Either you divide this piece of paper in half forever or you reach a point where it could no longer be divided in half and still be considered paper.

Open Ended

Do you think matter is continuous or made of tiny particles? Explain your answer and cite evidence from your life experiences.

Separating Water

During electrolysis, water (H₂O) is separated into oxygen and hydrogen, two pure substances. The two gases are collected in separate tubes.

Open Ended

An electrolysis device uses electricity to separate water into oxygen and hydrogen. When separated, the oxygen always takes up about half as much space as the hydrogen. What might this tell you about the materials that make up water?

Electrolysis of Water

• In 1803 John Dalton separated water into two components

• He realized they always separated into the same ratio

• Twice as much Hydrogen (H₂) than Oxygen (O)

Evidence for Particle Theory of Matter

One hypothesis was that large pieces of matter were made up of many tiny particles.

Brownian Motion

• In the late 1820s, Robert Brown noticed that pollen moved when placed in water (seen here -->)

• One idea was that there were tiny particles crashing into the pollen

Open Ended

How do the observations of Brownian motion support the idea that matter is made up of tiny particles?

Evidence from New Technologies

• Powerful microscopes have been able to create images of individual particles of matter

Open Ended

If matter is made of many tiny particles, why does it seem to be continuous? Why doesn’t water seem to behave like sand?